A number of methods of preparing poly(glycidyl azide) polymer from polyepichlorohydrin polymer by the nucleophilic displacement of leaving groups, e.g. chlorine atoms, present in the polyepichlorohydrin polymer with azide ion are known. For example, see U.S. Pat. Nos. 4,268,450 (Frankel et al), 4,379,894 (Frankel et al), 4,486,351 (Earl), 3,645,917 (Vandenberg), 4,879,419 (Johannessen) and 4,937,361 (Wagner et al).
U.S. Pat. No. 4,379,894 describes a process of reacting polyepichlorohydrin and sodium azide in an aqueous medium in the presence of a phase transfer catalyst. The '894 patent describes a reaction using one liter of water with 248 grams of polyepichlorohydrin and 211 grams of sodium azide. Although a reaction utilizing such a relatively large amount of water may, as noted in the '894 patent, avoid the expense of the dipolar aprotic solvents, it is believed that such reactions will be relatively slow. The '894 patent also states that tertiary amines and quaternary ammonium compounds can be used as phase transfer catalysts in the reaction. It is not believed that tertiary amines are very effective phase transfer catalysts for the polyepichlorohydrin-sodium azide reaction. While the '894 patent states that quaternary ammonium compounds can be used as phase transfer catalysts in the reaction, only methyl tricaprylammonium chloride and ALIQUAT.TM. 336 are specifically described or exemplified and it is believed that such compounds will undergo decomposition or degradation reactions during the polyepichlorohydrin-sodium azide reaction to form undesirable products, such as tertiary amines, which are not very useful in promoting the polyepichlorohydrin-azide reaction. Additionally, it is believed that such quaternary ammonium compounds are difficult to remove from the poly(glycidyl azide) polymer reducing their recyclability, and their undesirable decomposition or degradation products are also believed to be difficult to remove from the poly(glycidyl azide) polymer.
U.S. Pat. No. 4,937,361 describes a method of making a poly(glycidyl azide) polymer by reacting polyepichlorohydrin, sodium azide and "chlorides and bromides of quaternary ammonium and lithium cations" in a reaction solvent. The patent states that the chlorides and bromides of quaternary ammonium and lithium cations metathesize with the sodium azide to produce an azide compound that is more soluble than sodium azide in the reaction mixture, however, the only quaternary ammonium compounds specifically described or exemplified in the patent are methyltrioctylammonium chloride and dodecyltrimethylammonium chloride, and even in the organic reaction solvents described, such compounds are not believed to be particularly stable, and as explained above, both the quatrenary ammonium compounds and their degradation or decomposition products are believed to be difficult to remove from the poly(glycidyl azide) polymer.